No abstract

Fucoxanthin is an allenic carotenoid. Chemical and spectroscopic studies establish its structure as 3 '-acetoxy-5.6 -epoxy-3,5'-dihydroxy-6',7'-didehydro-5,6,7,8,5',6'-hexahydro-p-caroten-8-one (1 5).FUCOXANTHIN occurs in brown algae (Phaeophyceae) and in diatom^,^^^ and is probably the most abundant carotenoid in nature. Like chlorophyll b it is believed to act as an accessory pigment in photosynthesis.4 A role in the reproduction of brown algae has also been ~uggested.~ Fucoxanthin was first isolated in a crystalline state by Willstatter and Page in 1914 and, until recently, has been assigned a molecular formula of the type C,H,,-,,O, in keeping with the C40 formulation of most other carotenoids.2y6 The melting point of fucoxanthin has been reported as 159-160" and (after purification by chromatography on alumina) as 166-168'.Material with the lower m.p. was shown to be optically active,s but the higher melting product was originally reported to be optically i n a ~t i v e . ~ Since fucoxanthin is stereochemically labile, tends to solvate or occlude solvent, and is unstable to acids, alkalis, and oxygen, it was conceivable that the reported differences in physical properties were due to a structural or stereochemical difference in the two products. However, both melting

Studies on a sulfited glucose/glycine system showed that rapid color development, due to the Maillard reaction, did not begin until "free" SO, (i.e. sulfite/ bisulfite ion) had almost disappeared from the system. At this time "free" SOI was less than 5% of that added and 28% was present in reversible combination with, e.g., carbonyl compounds. These results are considered in relation to recently published hvootheses on the intermediates involved in the Maillard reaction and on its bined" SOz = 21.8% (theoretical = 22.8%).Color measurement inhibition' by sulfites.Color intensity was measured using a Unicam SP800 UV/visible spectrophotometer and a distilled water blank. The spectrum was recorded between 400 and 550 mp. Absorption at 490 rnh was used as a measurement of color intensity to allow direct comparison between the present work and that of Song et al. (1967b).